Adaptive immunity Flashcards
List the 6 cellular components and the humoral component of the adaptive immune system.
B-lymphocytes including plasma cells
Cytotoxic T- lymphocytes
Helper T- lymphocytes
Regulatory T- lymphocytes
Antigen-presenting cells
Memory cells
Antibodies (immunoglobulins, Ig – various classes)
Where do T cells mature?
Thymus gland
What is the function of B cells?
Produce antibodies (immunoglobulins)
What is the function of helper T cells?
Secrete cytokines that activate other immune cells
What is the function of cytotoxic T cells?
Directly kill infected cells and tumour cells
What happens when the an antigen binds to the antigen-receptor (surface immunoglobulin) on the surface of a B cell?
The B cell becomes activated and differentiates into a plasma cell, which are specialized in producing and secreting the same antibody at a high rate
How does the size of the nucleus and endoplasmic reticulum change as B cells differentiate into plasma cells and why?
The nucleus becomes smaller as a result of the increased size of the endoplasmic reticulum, because the endoplasmic reticulum is involved in the secretion of the soluble form of the immunoglobulin
Describe 3 ways in which antibody binding to an antigen can aid in the removal / destruction of pathogens.
Block a pathogen from causing harm
Mark a pathogen for phagocytosis (opsonisation)
Activate the complement system
Which feature of antigens means that different antibodies can bind to separate parts of the same antigen?
Epitopes
What is clonal selection in the adaptive immune response?
The activation and proliferation of a specific lymphocyte that produces the antibodies which bind the same antigen
Which cells are usually needed for the activation of B cells?
Helper T cells
Describe why a secondary antibody response to an antigen would be quicker and stronger than the primary antibody response.
Due to immunological memory – the first exposure produces clonal expansion to produce plasma cells and memory B cells. Upon subsequent exposure, the memory B cells recognise the antigen much more quickly
What is the typical antibody class switch in an immune response?
IgM to IgG
What is the cell surface protein of cytotoxic T cells?
CD8
What is the cell surface protein of helper T cells?
CD4
What is the function of TH1 cells and what do they activate?
Secrete cytokines (interferon-y) that mainly activate virally infected cells, macrophages, and other T cells
What is the function of TH2 cells and what do they activate?
Secrete cytokines (interleukins) that mainly activate B cells
Describe the structure of the T cell receptor and how this relates to antigen recognition.
TCRs are alpha beta heterodimers, with both the alpha chain and the beta chain having a constant and variable region each
The variable regions are where the antigen recognition occurs, as they form the binding site for the peptide-MHCs (i.e. antigen)
What are the MHC proteins, where are they present, and what are they recognised by?
MHC Class I – present on most cells, recognised by CD8+ cytotoxic T cells
MHC Class II – present on antigen-presenting cells, recognised by CD4+ helper T cells
Describe the structure of MHC Class I proteins.
Composed of an alpha chain and b2-microglobulin
The alpha chain forms the antigen-binding groove
Where are the peptides presented on MHC Class I proteins derived from?
Cell cytoplasm
Describe the structure of MHC Class II proteins.
Composed of alpha and beta chain which form the antigen-binding groove where peptides are displayed
Where are the peptides presented on MHC Class II proteins derived from?
Ingested material
Do CD4 and CD8 bind to the variable or non-variable parts of the MHC proteins?
Non-variable
